package com.tianji.learning.service.impl;

import cn.hutool.core.util.ObjectUtil;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.tianji.api.client.course.CatalogueClient;
import com.tianji.api.client.course.CourseClient;
import com.tianji.api.dto.course.CataSimpleInfoDTO;
import com.tianji.api.dto.course.CourseFullInfoDTO;
import com.tianji.api.dto.course.CourseSimpleInfoDTO;
import com.tianji.common.domain.dto.PageDTO;
import com.tianji.common.domain.query.PageQuery;
import com.tianji.common.exceptions.BadRequestException;
import com.tianji.common.exceptions.BizIllegalException;
import com.tianji.common.utils.BeanUtils;
import com.tianji.common.utils.CollUtils;
import com.tianji.common.utils.DateUtils;
import com.tianji.common.utils.UserContext;
import com.tianji.learning.domain.dto.LearningPlanDTO;
import com.tianji.learning.domain.enums.LessonStatus;
import com.tianji.learning.domain.enums.PlanStatus;
import com.tianji.learning.domain.po.LearningLesson;
import com.tianji.learning.domain.po.LearningRecord;
import com.tianji.learning.domain.vo.LearningLessonVO;
import com.tianji.learning.domain.vo.LearningPlanPageVO;
import com.tianji.learning.domain.vo.LearningPlanVO;
import com.tianji.learning.mapper.LearningLessonMapper;
import com.tianji.learning.mapper.LearningRecordMapper;
import com.tianji.learning.service.ILearningLessonService;
import com.tianji.learning.service.ILearningRecordService;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.LongStream;

/**
 * <p>
 * 学生课程表 服务实现类
 * </p>
 *
 * @author 东哥
 * @since 2024-11-06
 */
@Slf4j
@Service
@RequiredArgsConstructor
public class LearningLessonServiceImpl extends ServiceImpl<LearningLessonMapper, LearningLesson> implements ILearningLessonService {
    private final CourseClient courseClient;
    private final CatalogueClient catalogueClient;
    private final LearningRecordMapper recordMapper;

    /**
     * 1、添加到课程到课表（Day2 - 课堂1）
     *
     * @param userId    用户ID
     * @param courseIds 课程ID集合
     */
    @Override
    @Transactional
    public void addLessons(Long userId, List<Long> courseIds) {
        // 1、根据课程ID集合远程调用查询课程信息
        List<CourseSimpleInfoDTO> courseInfoList = courseClient.getSimpleInfoList(courseIds);
        if(ObjectUtil.isEmpty(courseInfoList)){
            log.error("课程信息不存在，无法把课程添加到课表");
            return;
        }
        // 2、循环组装课表数据
        List<LearningLesson> lessons = new ArrayList<>(courseInfoList.size());
        for (CourseSimpleInfoDTO courseInfo : courseInfoList) {
            LearningLesson lesson = new LearningLesson();
            // 2.1、填充userId、courseId
            lesson.setUserId(userId);
            lesson.setCourseId(courseInfo.getId());

            // 2.2、填充课程过期时间
            Integer validDuration = courseInfo.getValidDuration();
            if(ObjectUtil.isEmpty(validDuration) || validDuration <= 0){
                continue;
            }
            lesson.setExpireTime(LocalDateTime.now().plusMonths(validDuration));
            lessons.add(lesson);
        }

        // 3、批量新增
        saveBatch(lessons);
    }

    /**
     * 2、分页查询我的课表（Day2 - 课堂2）
     *
     * @param pageQuery 分页查询参数对象
     * @return
     */
    @Override
    public PageDTO<LearningLessonVO> pageQueryMyLessons(PageQuery pageQuery) {
        // 1、获取当前登录人
        Long userId = UserContext.getUser();

        // 2、发起分页查询
        // select * from learning_lesson where user_id = #{} order by lastest_learn_time desc limit 0,5
        /*Page<LearningLesson> page = Page.of(pageQuery.getPageNo(), pageQuery.getPageSize());
        if(ObjectUtil.isEmpty(pageQuery.getSortBy())){
            page.addOrder(OrderItem.desc("latest_learn_time"));
        }else{
            page.addOrder(new OrderItem(pageQuery.getSortBy(),pageQuery.getIsAsc()));
        }*/
        Page<LearningLesson> page = this.lambdaQuery()
                .eq(LearningLesson::getUserId, userId)
                .page(pageQuery.toMpPage("latest_learn_time", false));

        List<LearningLesson> records = page.getRecords();
        if(ObjectUtil.isEmpty(records)){
            return PageDTO.empty(page);
        }

        // 3、发起远程调用，查询课程详细信息（课程名称、封面、总课时数）
        Map<Long, CourseSimpleInfoDTO> courseInfoMap = queryCourseInfoAnd2Map(records);

        // 4、循环分页结果，将po list转为 vo list
        List<LearningLessonVO> vos = new ArrayList<>(records.size());
        for (LearningLesson lesson : records) {
            // 4.1、利用工具将lesson属性拷贝至vo中
            LearningLessonVO vo = BeanUtils.copyBean(lesson, LearningLessonVO.class);

            // 4.2、获取课程特有信息（课程名称、封面、总课时数），填充至vo
            /*for (CourseSimpleInfoDTO course : courseInfoList) {
                if(course.getId().equals(lesson.getCourseId())){
                    vo.setCourseName(course.getName());
                    vo.setCourseCoverUrl(course.getCoverUrl());
                    vo.setSections(course.getSectionNum());
                    break;
                }
            }*/
            CourseSimpleInfoDTO courseInfo = courseInfoMap.get(lesson.getCourseId());
            vo.setCourseName(courseInfo.getName());
            vo.setCourseCoverUrl(courseInfo.getCoverUrl());
            vo.setSections(courseInfo.getSectionNum());

            // 4.3、存入vo集合
            vos.add(vo);
        }

        // 5、封装最终的PageDTO并返回
        return PageDTO.of(page,vos);
    }

    /**
     * 收集records中的courseId，进行远程调用，获取课程信息并转为Map
     * @param records 课表信息集合
     * @return 课程信息Map  courseId -> course
     */
    private Map<Long, CourseSimpleInfoDTO> queryCourseInfoAnd2Map(List<LearningLesson> records) {
        // 3.1、收集当前页面的所有课程ID集合
        Set<Long> courseIds = records.stream().map(LearningLesson::getCourseId).collect(Collectors.toSet());

        // 3.2、发起远程调用
        List<CourseSimpleInfoDTO> courseInfoList = courseClient.getSimpleInfoList(courseIds);

        // 3.3、健壮性判断
        if(ObjectUtil.isEmpty(courseInfoList)){
            throw new BizIllegalException("课程信息不存在！");
        }

        // 3.4、将list转换为map，共后续高效使用
        Map<Long, CourseSimpleInfoDTO> courseInfoMap = courseInfoList.stream()
                .collect(Collectors.toMap(CourseSimpleInfoDTO::getId, Function.identity()));
        return courseInfoMap;
    }

    /**
     * 3、查询我正在学习的课程（Day2 - 作业1）
     * @return
     */
    @Override
    public LearningLessonVO queryMyCurrentLesson() {
        // 1.获取当前登录的用户
        Long userId = UserContext.getUser();
        // 2.查询正在学习的课程 select * from xx where user_id = #{userId} AND status = 1 order by latest_learn_time limit 1
        LearningLesson lesson = lambdaQuery()
                .eq(LearningLesson::getUserId, userId)
                .eq(LearningLesson::getStatus, LessonStatus.LEARNING.getValue())
                .orderByDesc(LearningLesson::getLatestLearnTime)
                .last("limit 1")
                .one();
        if (lesson == null) {
            return null;
        }
        // 3.拷贝PO基础属性到VO
        LearningLessonVO vo = BeanUtils.copyBean(lesson, LearningLessonVO.class);
        // 4.查询课程信息
        CourseFullInfoDTO cInfo = courseClient.getCourseInfoById(lesson.getCourseId(), false, false);
        if (cInfo == null) {
            throw new BadRequestException("课程不存在");
        }
        vo.setCourseName(cInfo.getName());
        vo.setCourseCoverUrl(cInfo.getCoverUrl());
        vo.setSections(cInfo.getSectionNum());
        // 5.统计课表中的课程数量 select count(1) from xxx where user_id = #{userId}
        Integer courseAmount = lambdaQuery()
                .eq(LearningLesson::getUserId, userId)
                .count();
        vo.setCourseAmount(courseAmount);
        // 6.查询小节信息
        List<CataSimpleInfoDTO> cataInfos =
                catalogueClient.batchQueryCatalogue(CollUtils.singletonList(lesson.getLatestSectionId()));
        if (!CollUtils.isEmpty(cataInfos)) {
            CataSimpleInfoDTO cataInfo = cataInfos.get(0);
            vo.setLatestSectionName(cataInfo.getName());
            vo.setLatestSectionIndex(cataInfo.getCIndex());
        }
        return vo;
    }

    /**
     * 4、查询指定课程信息（Day2 - 作业2）
     * @param courseId
     * @return
     */
    @Override
    public LearningLessonVO queryLessonByCourseId(Long courseId) {
        // 1.获取当前登录用户
        Long userId = UserContext.getUser();
        // 2.查询课程信息 select * from xx where user_id = #{userId} AND course_id = #{courseId}
        LearningLesson lesson = getOne(buildUserIdAndCourseIdWrapper(userId, courseId));
        if (lesson == null) {
            return null;
        }
        // 3.处理VO
        return BeanUtils.copyBean(lesson, LearningLessonVO.class);
    }

    /**
     * 5、删除指定课程信息（Day2 - 作业3）
     * @param userId
     * @param courseId
     */
    @Override
    public void deleteCourseFromLesson(Long userId, Long courseId) {
        // 1.获取当前登录用户
        if (userId == null) {
            userId = UserContext.getUser();
        }
        // 2.删除课程
        remove(buildUserIdAndCourseIdWrapper(userId, courseId));
    }

    /**
     * 6、统计课程学习人数（Day2 - 作业4）
     * @param courseId
     * @return
     */
    @Override
    public Integer countLearningLessonByCourse(Long courseId) {
        // select count(1) from xx where course_id = #{cc} AND status in (0, 1, 2)
        return lambdaQuery()
                .eq(LearningLesson::getCourseId, courseId)
                .in(LearningLesson::getStatus,
                        LessonStatus.NOT_BEGIN.getValue(),
                        LessonStatus.LEARNING.getValue(),
                        LessonStatus.FINISHED.getValue())
                .count();
    }

    /**
     * 7、校验当前课程是否已经报名（Day2 - 作业5）
     * @param courseId
     * @return
     */
    @Override
    public Long isLessonValid(Long courseId) {
        // 1.获取登录用户
        Long userId = UserContext.getUser();
        if (userId == null) {
            return null;
        }
        // 2.查询课程
        LearningLesson lesson = getOne(buildUserIdAndCourseIdWrapper(userId, courseId));
        if (lesson == null || LessonStatus.EXPIRED.equals(lesson.getStatus())) {
            return null;
        }
        return lesson.getId();
    }

    /**
     * 8、创建或修改学习计划（Day3 - 课堂3）
     *
     * @param planDTO
     */
    @Override
    public void createPlans(LearningPlanDTO planDTO) {
        // 1、查询课表信息（courseId、userId）
        LearningLesson lesson = getOne(buildUserIdAndCourseIdWrapper(UserContext.getUser(), planDTO.getCourseId()));

        // 2、更新学习计划数据
        this.lambdaUpdate()
                .set(LearningLesson::getWeekFreq, planDTO.getFreq())
                .set(lesson.getPlanStatus() == PlanStatus.NO_PLAN,LearningLesson::getPlanStatus, PlanStatus.PLAN_RUNNING)
                .eq(LearningLesson::getId,lesson.getId())
                .update();
    }

    /**
     * 9、查询我的学习计划（Day3 - 课堂4）
     *
     * @param pageQuery
     * @return
     */
    @Override
    public LearningPlanPageVO queryMyPlans(PageQuery pageQuery) {
        LearningPlanPageVO vo = new LearningPlanPageVO();
        // 1、获取当前登录用户
        Long userId = UserContext.getUser();

        // 2、分页查询我的课表（我的、创建过学习计划、状态是未学习、学习中，根据最近学习时间倒序排序）
        Page<LearningLesson> pageResult = this.lambdaQuery()
                .eq(LearningLesson::getUserId, userId)
                .eq(LearningLesson::getPlanStatus, PlanStatus.PLAN_RUNNING)
                .in(LearningLesson::getStatus, LessonStatus.NOT_BEGIN, LessonStatus.LEARNING)
                .page(pageQuery.toMpPage("latest_learn_time", false));
        List<LearningLesson> records = pageResult.getRecords();
        if(ObjectUtil.isEmpty(records)){
            return vo.emptyPage(pageResult);
        }

        // 3、查询课程填充数据（根据课程ID集合查询课程信息）
        Map<Long, CourseSimpleInfoDTO> courseInfoMap = queryCourseInfoAnd2Map(records);

        // 4、统计学习记录表中本周学习小节数据
        //select r.`lesson_id`as id,count(1) as num from learning_record r where r.`user_id` = 2 and r.`finished` = 1
        //and r.`finish_time` between '2024-11-04 00:00:00' and '2024-11-10 23:59:59'
        //group by r.`lesson_id`
        // 4.1、获取本周开始、结束日期
        LocalDateTime begin = DateUtils.getWeekBeginTime(LocalDate.now());
        LocalDateTime end = DateUtils.getWeekEndTime(LocalDate.now());
        QueryWrapper<LearningRecord> queryWrapper = new QueryWrapper<>();
        queryWrapper.select("`lesson_id`as id,count(1) as num")
                .eq("user_id",userId)
                .eq("finished",true)
                .between("finish_time",begin,end)
                .groupBy("lesson_id");

        List<Map<String, Object>> mapList = recordMapper.selectMaps(queryWrapper);
        Map<Long, Long> learnedSectionNumMap = mapList.stream()
                .collect(Collectors.toMap(r -> (Long) r.get("id"), r -> (Long) r.get("num")));

        // 5、循环之前查询的分页课表数据，进行数据填充
        List<LearningPlanVO> voList = new ArrayList<>(records.size());
        for (LearningLesson record : records) {
            // 5.1、拷贝po至vo
            LearningPlanVO learningPlanVO = BeanUtils.copyBean(record, LearningPlanVO.class);

            // 5.2、填充课程数据
            CourseSimpleInfoDTO couseInfo = courseInfoMap.get(record.getCourseId());
            if(ObjectUtil.isNotEmpty(couseInfo)){
                learningPlanVO.setCourseName(couseInfo.getName());
                learningPlanVO.setSections(couseInfo.getSectionNum());
            }

            // 5.3、填充本周已学习小节数
            learningPlanVO.setWeekLearnedSections(learnedSectionNumMap.getOrDefault(record.getId(),0L).intValue());

            // 5.4、添加vo至list
            voList.add(learningPlanVO);
        }

        // 6、计算本周计划学习的总小节数
        //select sum(week_freq) from learning_lesson where user_id = 2 and plan_status = 1
        //and status in (0,1)
        LearningLesson lesson = this.query()
                .select("sum(week_freq) as total_weekfreq")
                .eq("user_id", userId)
                .eq("plan_status", PlanStatus.PLAN_RUNNING)
                .in("status", LessonStatus.NOT_BEGIN, LessonStatus.LEARNING)
                .one();

        // 7、计算本周已学习的总小节数
        long sum = learnedSectionNumMap.values().stream().mapToLong(num -> num.longValue()).sum();
        Integer weekFinished = Long.valueOf(sum).intValue();

        /*long sum1 = learnedSectionNumMap.values().stream().flatMapToLong(num -> LongStream.of(num)).sum();
        Long sum2 = learnedSectionNumMap.values().stream().map(Function.identity()).reduce(Long::sum).get();
        Long sum3 = learnedSectionNumMap.values().stream().collect(Collectors.summingLong(num -> num));
        long sum4 = learnedSectionNumMap.values().stream().mapToLong(num -> num).summaryStatistics().getSum();*/

        // 8、封装Vo并返回
        vo.setWeekTotalPlan(lesson.getTotalWeekfreq());
        vo.setWeekFinished(weekFinished);
        vo.setWeekPoints(null); // TODO 本周学习积分
        return vo.pageInfo(pageResult.getTotal(),pageResult.getPages(),voList);
    }


    private LambdaQueryWrapper<LearningLesson> buildUserIdAndCourseIdWrapper(Long userId, Long courseId) {
        LambdaQueryWrapper<LearningLesson> queryWrapper = Wrappers.<LearningLesson>lambdaQuery()
                .eq(LearningLesson::getUserId, userId)
                .eq(LearningLesson::getCourseId, courseId);
        return queryWrapper;
    }
}
